Vibrating finishing screed



March 24-, 1936. DQDDS 2,034,942

VIB'RATING FINISHING SCREED Filed May 17, 1932 Dos. 32. 35 H s S g L I 34 Q E Patented Mar. 24, 1936 UNITED STATES PATENT OFFICE 7 Claims.

The invention relates to an improvement in means and method of finishing the surface of plastic slabs or constructions wherein the material has been positioned and must be smoothed prior to hardening.

It is one of the objects of the invention to provide a screed or finishing machine which is adapted to vibrate in order to effect a smooth compact finished surface on a plastic mass.

Another object of the invention is to provide a screed which is arranged for vertical vibration without any lateral movement in order to finish a concrete surface.

Another object of the invention is to simplify the construction, arrangement and operation of finishing machines with a view of obtaining an improved finish on concrete surfaces.

Another object of the inventionis to provide a vibrating screed which is adjustable with re- 'spcct to its supporting structure so that the same may be positioned to obtain a finish at any desired elevation.

Another object of the invention is to provide in combination with a finishing screed a vibrating element to agitate the screed along a normal to the surface being finished without applying lateral movement to the screed.

Other and further objects of the invention will be readily apparent when the following description is considered in connection with the accompanying drawing wherein Fig. 1 is a front elevation of the vibrating screed which embodies one form of the invention.

Fig. 2 is a sectional view taken on the line 22 of Fig. 1, and looking in the direction of the arrows.

Fig. 3 is a top plan view looking down on the vibrating screed and showing the parts in elevation.

Fig. 4 is a section taken on the line 4-4 of Fig. 1, and showing the internal construction of the vibrators, which may be used in connection with the invention.

It has long been the practice in finishing plastic surfaces to trowel the surface by hand or to smooth the same with various types of screeds or straight edges; various types of finishing machineshave been devised to move the screed by power, and in a majority of instances these maent invention, however, it has been found that very satisfactory results are obtained by dispensing with'the sawing action of the screed and merely vibrating the screed along a normal to the surface being finished in order to obtain a 5 smooth surface.

The invention has been shown in connection with a finishing machine for roadways or pavements. It is intended, however, that it may be used under any desired circumstances. Fig. 1 10 shows the forms and 2, which serve to confine the material being placed and it is upon these forms that the carriage 3 is mounted to travel. This carriage may take any desired form but preferably has the wheel supports 4 and 5, so 15 that it may be moved along the mass being surfaced.

A suitable power unit may be incorporated as at 6, with a driving mechanism 1, which is applied to one of the axles of the carriage. In the present instance the power unit may be an electric motor or, if desired, the entire carriage 3 may be attached to a larger machine such as the mixer or other apparatus used in connection with the laying of concrete. The present invention is 25 of particular advantage when used in connection with the means and method of laying concrete which is disclosed in the application for patent of Stanley S. Dodds and James D. French Serial No. 606,056 filed April 18, 1932, wherein a general 30 showing of the present invention has been incorporated.

It is intended that the carriage 3 will be moved along the forms or otherwise supported for movement above the plastic mass In, which is being 35 surfaced. With a view of smoothing the surface of this mass ID, a screed or straight edge II has been provided. This screed is in the form of a suitable transverse beam or bar I2, which is supported from the carriage 3. The supportfor the 40 screed l I may be in the form of a chain or flexible element l3, which is carried by the arm l4, mounted on the carriage 3. In order that the screed and the arm may be adjusted as to elevation with respect to the carriage and the sur- 45 face being finished, an adjustable rod I5 is connected to the shaft l6 upon which the arms M are mounted. A suitable control lever l8 may be adjusted on the circular rack H in order to support the screed in any desired adjusted posi- 50 tion.

The screed l2 may take different forms in order to obtain the desired surface on the plastic mass. The present drawing shows the screed a channel member disposed edgewise of the surface and 55 as having. the vertical portion 20, which is connected'with an extended base or leg 2|. This base 2| is arranged to contact with the plastic mass it and serves to tamp or pat the surface to obtain the desired finish. The forward part Of the screed at the lower side of the web is provided with a replaceable blade or bar 22, which takes the wear due to contact of the screed with the concrete. A mass of concrete 2! is shown as having accumulated in front of the screed.

It is intended that the screed or straight edge will be vibrated along a normal to the surface of th plastic mass Ill, so that each time the screed m'oves upwardly away from the surface a small amount of the accumulated material at 23 will move beneath the blade 22. To properly position the screed with respect to the carriage, the struts or push bars 25 have been provided and may be connected to the front axle 26 of the carriage 3. These push bars are connected not only to the'axle 26 but also to the screed as at 21, so that the vibration of the screed will not be transmitted to the carriage 3.

It is intended that the screed I I will be of sturdy construction and it may be formed of wood or it may be a steel beam. In either event, a plurality "of vibrating elements 30 may be positioned directly upon the beam. These elements may take the form shown in Fig. 4 and embody a power unit 3|, which has a shaft 32 mounted in the bearing 33 and an eccentric 34 which is carried by the shaft and tends to vibrate the housing as, m

In actual use the present invention has given,

very satisfactory results in providing a smooth compact surface which may be obtained at a greater rate than with the present types of finishing machines. The actionbf the vibrating screed without the sawing action not only results in a compacted surface but also simplifies the cumbersome mechanism required when a latoral or sawingmotion is applied to the screed. .Vlghat is claimed is: i

'1. Avibrating screed including a body, a forwardlv inclined blade thereon adapted to have a 'mass of concrete upon and before it, a fiat convibration of the screed.

to retain said screed in front of said frame, ad- Justable support means for said screed also on said frame, means on the screed to vibrate it on a normal tothe surface, and aforwardly extending bar on said screed from which the accumulating material is fed beneath the screed at each vibration.

3. In a road surfacing machine a vibrating screed, said screed comprising a channel member disposed edgewise with respect to the surface, the lower leg of said channel being extended rearwardly to tamp the surface, and a forwardly extending downwardly inclined bar on the front edge of the channel forming a shelf to carry a mass of concrete and from which the concrete will slide during the vibration of the screed.

4. In a concrete road surfacing machine, a frame, wheels on said frame whereby it may be moved along the forms, a driving motor connected to said wheels, a surfacing screed. disposed in front of said frame, pivoted push bars main taining said screed against horizontal displacement, ratchet means connected to said screed to provide vertical adjustment with respect to the forms, a vibrator carried by said screed and adapted to vibrate it vertically, and a forwardly extending bar on the front edge of said screed, said screed being adapted to form a combined cut off tamp and finishing member.

5. A concrete road surfacing device including a four wheeled carriage, a frame therefor, a motor to propel said carriage along the forms, a transverse finishing screed positioned ahead of said carriage, pivoted links connecting said screed and one of the axles of the carriage, said links supporting said screed against horizontal movement only, a ratchet adjuster to vary the elevation at which the screed is supported, vibrators on said screed whereby it may be vibrated vertically, and

a forwardly extending bar on the front edge of said screed to engagethe material to be cut off, tamped and finished.

6. A screed for finishing plastic surfaces including a carriage, a screed bar, means on said carriage adjustably supporting said bar for vertical vibratory movement with respect to such carriage, said means including a lever, means to regulate the elevation of said bar by setting said lever in intermediate adjusted position, and means mounted on said bar to vibrate the same in a vertical plane.

'7. A vibrating screed for finishing concrete including a bar to engage the surface, a lever to adjustably position said bar including a rack and pawl regulation therefor, vibrators connected to said bar to cause vibration thereof along a normal to the surface being finished, and means on said screed to move material thereunder upon STANLEY S. 

